Adafruit PiRTC - Precise DS3231 Real Time Clock for Raspberry Pi

Key Features:

• Best battery-backed RTC you can get that allows your Raspberry Pi project to keep track of time if the power is lost
• Perfect for data-logging, clock-building, NTP servers, time-stamping, timers and alarms
• 100% genuine Maxim DS3231 board
• Works perfectly with any Raspberry Pi (Pi 1, Pi 2, Pi 3, Pi 4, Pi Zero, A+, B+ etc. )

This is the best battery-backed real time clock (RTC) you can get that allows your Raspberry Pi project to keep track of time if the power is lost. Perfect for data-logging, clock-building, NTP servers, time-stamping, timers and alarms, etc. Equipped with a genuine DS3231 RTC, it works great with the Raspberry Pi and has native kernel support. This Real Time Clock (RTC) is the most precise you can get in a small, low power package.

Most RTCs use an external 32kHz timing crystal that is used to keep time with low current draw. And that' s all well and good, but those crystals have slight drift, particularly when the temperature changes (the temperature changes the oscillation frequency very very very slightly but it does add up! ) This RTC is in a beefy package because the crystal is inside the chip! And right next to the integrated crystal is a temperature sensor.

That sensor compensates for the frequency changes by adding or removing clock ticks so that the timekeeping stays on schedule.

Item Specific
Fully assembled & tested PCB plugs directly into your Pi' s GPIO pins
No soldering required
Will keep time for 5 years or more
Size: 21.3 mm x 20.0 mm x 13.6 mm / 0.8" x 0.8" x 0.5"
Weight: 2.7 g / 0.1 oz
CR1220 coin cell battery not included